Who are the religious and ethnic groups under threat from ISIS?

By Joshua Berlinger, CNN

Updated 10:51 PM ET, Fri August 8, 2014

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Photos:The ISIS terror threat

Wounded passengers are treated following a suicide bombing at the Brussels Airport on March 22, 2016. The attacks on the airport and a subway killed 32 people and wounded more than 300. ISIS claims its "fighters" launched the attacks in the Belgian capital.

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Photos:The ISIS terror threat

Syrians gather at the site of a double car bomb attack in the Al-Zahraa neighborhood of the Homs, Syria, on February 21, 2016. Multiple attacks in Homs and southern Damascus kill at least 122 and injure scores, according to the state-run SANA news agency. ISIS claimed responsibility.

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Syrian pro-government forces gather at the site of a deadly triple bombing Sunday, January 31, in the Damascus suburb of Sayeda Zeynab. ISIS claimed responsibility for the attack, according to a statement circulating online from supporters of the terrorist group.

Wounded people are helped outside the Bataclan concert hall in Paris following a series of coordinated attacks in the city on Friday, November 13. The militant group ISIS claimed responsibility for the attacks, which killed at least 130 people and wounded hundreds more.

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Emergency personnel and civilians gather at the site of a twin suicide bombing in Beirut, Lebanon, on Thursday, November 12. The bombings killed at least 43 people and wounded more than 200 more. ISIS appeared to claim responsibility in a statement posted on social media.

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Smoke rises over the northern Iraqi town of Sinjar on November 12. Kurdish Iraqi fighters, backed by a U.S.-led air campaign, retook the strategic town, which ISIS militants overran last year. ISIS wants to create an Islamic state across Sunni areas of Iraq and Syria.

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Syrian government troops walk inside the Kweiras air base on Wednesday, November 11, after they broke a siege imposed by ISIS militants.

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Members of the Egyptian military approach the wreckage of a Russian passenger plane Sunday, November 1, in Hassana, Egypt. The plane crashed the day before, killing all 224 people on board. ISIS claimed responsibility for downing the plane, but the group's claim wasn't immediately verified.

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An explosion rocks Kobani, Syria, during a reported car bomb attack by ISIS militants on Tuesday, October 20.

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Shiite fighters, fighting alongside Iraqi government forces, fire a rocket at ISIS militants as they advance toward the center of Baiji, Iraq, on Monday, October 19.

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Smoke rises above a damaged building in Ramadi, Iraq, following a coalition airstrike against ISIS positions on Saturday, August 15.

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Iraqi men look at damage following a bomb explosion that targeted a vegetable market in Baghdad on Thursday, August 13. ISIS claimed responsibility for the attack.

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Photos:The ISIS terror threat

In this image taken from social media, an ISIS fighter holds the group's flag after the militant group overran the Syrian town of al-Qaryatayn on Thursday, August 6, the London-based Syrian Observatory for Human Rights reported. ISIS uses modern tools such as social media to promote reactionary politics and religious fundamentalism. Fighters are destroying holy sites and valuable antiquities even as their leaders propagate a return to the early days of Islam.

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An ISIS fighter poses with spoils purportedly taken after capturing the Syrian town of al-Qaryatayn.

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Smoke rises as Iraqi security forces bomb ISIS positions in the eastern suburbs of Ramadi, Iraq, on August 6.

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Buildings reduced to piles of debris can be seen in the eastern suburbs of Ramadi on August 6.

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The governor of the Asir region in Saudi Arabia, Prince Faisal bin Khaled bin Abdulaziz, left, visits a man who was wounded in a suicide bombing attack on a mosque in Abha, Saudi Arabia, on August 6. ISIS claimed responsibility for the explosion, which killed at least 13 people and injured nine others.

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Saudi officials and investigators check the inside of the mosque on August 6.

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Mourners in Gaziantep, Turkey, grieve over a coffin Tuesday, July 21, during a funeral ceremony for the victims of a suspected ISIS suicide bomb attack. That bombing killed at least 31 people in Suruc, a Turkish town that borders Syria. Turkish authorities blamed ISIS for the attack.

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Protesters in Istanbul carry anti-ISIS banners and flags to show support for victims of the Suruc suicide blast during a demonstration on Monday, July 20.

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People in Ashmoun, Egypt, carry the coffin for 1st Lt. Mohammed Ashraf, who was killed when the ISIS militant group attacked Egyptian military checkpoints on Wednesday, July 1. At least 17 soldiers were reportedly killed, and 30 were injured.

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Syrians wait near the Turkish border during clashes between ISIS and Kurdish armed groups in Kobani, Syria, on Thursday, June 25. The photo was taken in Sanliurfa, Turkey. ISIS militants disguised as Kurdish security forces infiltrated Kobani on Thursday and killed "many civilians," said a spokesman for the Kurds in Kobani.

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Residents examine a damaged mosque after an Iraqi Air Force bombing in the ISIS-seized city of Falluja, Iraq, on Sunday, May 31. At least six were killed and nine others wounded during the bombing.

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People search through debris after an explosion at a Shiite mosque in Qatif, Saudi Arabia, on Friday, May 22. ISIS claimed responsibility for the attack, according to tweets from ISIS supporters, which included a formal statement from ISIS detailing the operation.

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Iraqi soldiers fire their weapons toward ISIS group positions in the Garma district, west of the Iraqi capital of Baghdad, on Sunday, April 26. Pro-government forces said they had recently made advances on areas held by Islamist jihadists.

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Photos:The ISIS terror threat

A member of Afghanistan's security forces stands at the site where a suicide bomber on a motorbike blew himself up in front of the Kabul Bank in Jalalabad, Afghanistan, on Saturday, April 18. ISIS claimed responsibility for the attack. The explosion killed at least 33 people and injured more than 100 others, a public health spokesman said.

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Iraqi counterterrorism forces patrol in Ramadi on April 18.

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Thousands of Iraqis cross a bridge over the Euphrates River to Baghdad as they flee Ramadi on Friday, April 17.

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Yazidis embrace after being released by ISIS south of Kirkuk, Iraq, on Wednesday, April 8. ISIS released more than 200 Yazidis, a minority group whose members were killed, captured and displaced when the Islamist terror organization overtook their towns in northern Iraq last summer, officials said.

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Kurdish Peshmerga forces help Yazidis as they arrive at a medical center in Altun Kupri, Iraq, on April 8.

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A Yazidi woman mourns for the death of her husband and children by ISIS after being released south of Kirkuk on April 8. ISIS is known for killing dozens of people at a time and carrying out public executions, crucifixions and other acts.

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People in Tikrit inspect what used to be a palace of former President Saddam Hussein on April 3.

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On April 1, Shiite militiamen celebrate the retaking of Tikrit, which had been under ISIS control since June. The push into Tikrit came days after U.S.-led airstrikes targeted ISIS bases around the city.

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Iraqi security forces launch a rocket against ISIS positions in Tikrit on Monday, March 30.

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The parents of 19-year-old Mohammed Musallam react at the family's home in the East Jerusalem Jewish settlement of Neve Yaakov on Tuesday, March 10. ISIS released a video purportedly showing a young boy executing Musallam, an Israeli citizen of Palestinian descent who ISIS claimed infiltrated the group in Syria to spy for the Jewish state. Musallam's family told CNN that he had no ties with the Mossad, Israel's spy agency, and had, in fact, been recruited by ISIS.

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Iraqi Shiite fighters cover their ears as a rocket is launched during a clash with ISIS militants in the town of Al-Alam, Iraq, on Monday, March 9.

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Displaced Assyrian women who fled their homes due to ISIS attacks pray at a church on the outskirts of Damascus, Syria, on Sunday, March 1. ISIS militants abducted at least 220 Assyrians in Syria.

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Safi al-Kasasbeh, right, receives condolences from tribal leaders at his home village near Karak, Jordan, on Wednesday, February 4. Al-Kasasbeh's son, Jordanian pilot Moath al-Kasasbeh, was burned alive in a video that was recently released by ISIS militants. Jordan is one of a handful of Middle Eastern nations taking part in the U.S.-led military coalition against ISIS.

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A Kurdish marksman looks over a destroyed area of Kobani on Friday, January 30, after the city had been liberated from the ISIS militant group. The Syrian city, also known as Ayn al-Arab, had been under assault by ISIS since mid-September.

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Kurdish people celebrate in Suruc, Turkey, near the Turkish-Syrian border, after ISIS militants were expelled from Kobani on Tuesday, January 27.

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Collapsed buildings are seen in Kobani on January 27 after Kurdish forces took control of the town from ISIS.

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Junko Ishido, mother of Japanese journalist Kenji Goto, reacts during a news conference in Tokyo on Friday, January 23. ISIS would later kill Goto and another Japanese hostage, Haruna Yukawa.

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ISIS militants are seen through a rifle's scope during clashes with Peshmerga fighters in Mosul, Iraq, on Wednesday, January 21.

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An elderly Yazidi man arrives in Kirkuk after being released by ISIS on Saturday, January 17. The militant group released about 200 Yazidis who were held captive for five months in Iraq. Almost all of the freed prisoners were in poor health and bore signs of abuse and neglect, Kurdish officials said.

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Smoke billows behind an ISIS sign during an Iraqi military operation to regain control of the town of Sadiyah, about 95 kilometers (60 miles) north of Baghdad, on Tuesday, November 25.

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Fighters from the Free Syrian Army and the Kurdish People's Protection Units join forces to fight ISIS in Kobani on Wednesday, November 19.

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A picture taken from Turkey shows smoke rising after ISIS militants fired mortar shells toward an area controlled by Syrian Kurdish fighters near Kobani on Monday, November 3.

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Iraqi special forces search a house in Jurf al-Sakhar, Iraq, on Thursday, October 30, after retaking the area from ISIS.

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ISIS militants stand near the site of an airstrike near the Turkey-Syria border on Thursday, October 23. The United States and several Arab nations have been bombing ISIS targets in Syria to take out the militant group's ability to command, train and resupply its fighters.

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Kurdish fighters walk to positions as they combat ISIS forces in Kobani on Sunday, October 19.

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Heavy smoke rises in Kobani following an airstrike by the U.S.-led coalition on October 18.

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Cundi Minaz, a female Kurdish fighter, is buried in a cemetery in the southeastern Turkish town of Suruc on Tuesday, October 14. Minaz was reportedly killed during clashes with ISIS militants in nearby Kobani.

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Kiymet Ergun, a Syrian Kurd, celebrates in Mursitpinar, Turkey, after an airstrike by the U.S.-led coalition in Kobani on Monday, October 13.

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Alleged ISIS militants stand next to an ISIS flag atop a hill in Kobani on Monday, October 6.

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A Kurdish Peshmerga soldier who was wounded in a battle with ISIS is wheeled to the Zakho Emergency Hospital in Duhuk, Iraq, on Tuesday, September 30.

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Syrian Kurds wait near a border crossing in Suruc as they wait to return to their homes in Kobani on Sunday, September 28.

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A elderly man is carried after crossing the Syria-Turkey border near Suruc on Saturday, September 20.

Kurdish Peshmerga fighters fire at ISIS militant positions from their position on the top of Mount Zardak, east of Mosul, Iraq, on Tuesday, September 9.

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Displaced Iraqis receive clothes from a charity at a refugee camp near Feeshkhabour, Iraq, on Tuesday, August 19.

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Aziza Hamid, a 15-year-old Iraqi girl, cries for her father while she and some other Yazidi people are flown to safety Monday, August 11, after a dramatic rescue operation at Iraq's Mount Sinjar. A CNN crew was on the flight, which took diapers, milk, water and food to the site where as many as 70,000 people were trapped by ISIS. But only a few of them were able to fly back on the helicopter with the Iraqi Air Force and Kurdish Peshmerga fighters.

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Thousands of Yazidis are escorted to safety by Kurdish Peshmerga forces and a People's Protection Unit in Mosul on Saturday, August 9.

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Thousands of Yazidi and Christian people flee Mosul on Wednesday, August 6, after the latest wave of ISIS advances.

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A Baiji oil refinery burns after an alleged ISIS attack in northern Selahaddin, Iraq, on Thursday, July 31.

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A Syrian rebel fighter lies on a stretcher at a makeshift hospital in Douma, Syria, on Wednesday, July 9. He was reportedly injured while fighting ISIS militants.

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Children stand next to a burnt vehicle during clashes between Iraqi security forces and ISIS militants in Mosul on Tuesday, June 10.

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Story highlights

Nearly 40,000 Yazidis are trapped on the top of Mount Sinjar

The Islamic State has forced hundreds of thousands of minorities from their homes

The U.S. has sent them humanitarian airdrops and authorized air airstrikes

In a church in Irbil, 40-day-old Yeshua lies asleep in a crib, his sister playfully rocking him. It's a peaceful scene. Their mother watches over them, but her face shows the fear and despair many Iraqi minorities have felt over the past few days.

The Sunni militant group ISIS, which calls itself the Islamic State, has steamrolled into Iraq's north, forcing hundreds of thousands of minorities from their homes. The militants have beheaded some who won't bend to their will and are "putting people's heads on spikes" to terrorize others, a senior U.S. administration official said.

Nearly 40,000 Yazidis are trapped on the top of Mount Sinjar with few resources; many with just the clothes on their back, U.S. President Barack Obama said in an address late Thursday evening.

"These innocent families are faced with a horrible choice," Obama said. "Descend the mountain and be slaughtered, or stay and slowly die of thirst and hunger."

So who are these people being threatened by the Islamic State? And why do the militant Islamists have them in their cross hairs?

The Yazidis

The Yazidis are one of the world's smallest and oldest monotheistic religious minorities. Their religion is considered a pre-Islamic sect that draws from Christianity, Judaism and the ancient monotheistic religion of Zoroastrianism.

Yazidis worship one God and honor seven angels. Unlike Muslims and Christians, they reject the idea of sin, the devil and hell itself.

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Their religious differences have made them a target for persecution throughout history, most recently during the U.S. war in Iraq -- in 2007, more than 700 people were killed when suicide bombers attacked a Yazidi village. Before that, they were targeted for centuries under the rule of the Ottoman Empire.

Like the Kurds, they mostly reside in Iraq's north, many in the town of Sinjar in northwestern Nineveh province, bordering Iraq's Kurdish region. The province is home to mostly Arabs and Kurds, who have jostled for control over it for centuries.

But Yazidis also reside in Turkey, Syria, Armenia, Iran and parts of the Caucasus region.

The people speak Kurdish and are of Kurdish descent, but most see themselves as ethnically distinctive.

Iraqi Christians

Before being targeted by ISIS, an enormous portion -- some say as many as half -- of Iraq's Christians fled the country at the start of the U.S. war in 2003. Al Qaeda in Iraq, which preceded ISIS, brutally targeted the country's Christian minority.

According to the State Department, Christian leaders and nongovernmental organizations estimate that there are approximately 500,000 Christians in Iraq -- a that figure has declined by nearly 300,000 in the last five years. At one point there were over a million Christians living in Iraq.

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Most Iraqi Christians are Chaldeans, who are communicants with the Roman Catholic church. They predominantly reside in northern Iraq.

The al Qaeda splinter group has taken control of the country's largest Christian city, Qaraqosh. And last month, Christians in the country's second largest city, Mosul, were told they must convert to Islam, pay a fine or face "death by the sword."

"Christian communities are particularly affected: a people fleeing from their villages because of the violence that rages in these days, wreaking havoc on the entire region," said the Rev. Federico Lombardi, a spokesman for Pope Francis.

The Pope said on Twitter: "I ask all men and women of goodwill to join me in praying for Iraqi Christians and all vulnerable populations."

Sunni Turkmen make up 1% to 2% of Iraq's population, according to the State Department. A smaller group of Shia Turkmen live there, as well.

Shiites

Despite the risk ISIS poses to Yazidis, Turkmen, Christians and the country's other minorities, the risk to Iraq's majority Shia Muslims is far more widespread.

In their quest to create an Islamic caliphate stretching from Syria to Iraq, ISIS has targeted Shiites in both countries.

In June, the group claimed on Twitter that it killed at least 1,700 Shiites in June. ISIS is also fighting Syrian President Bashar al-Assad's forces in Syria. Assad is a member of the Alawite sect, on offshoot of Shia Islam.

Like many of the minorities in in the Nineveh province, Shiites and Alawites have been labeled as infidels by ISIS.

Shiites outnumber Sunnis in Iraq on the whole. Most of Baghdad is predominantly Shiite, but large portions of Iraq's western and northern territories contain Sunni majority populations.